Effect of Pregnant Mare's Serum on the Immature Fowl

Abstract

Precocious development of immature male fowl has been induced by injection of extracts from the anterior lobe of the pituitary 1 , 2 and by pregnant mare's serum. 3 Less marked response of the ovary, oviduct and head furnishings to extracts of the anterior pituitary has been obtained in the immature female fowl 1 while oestrin induces precocious development of the oviduct only. 4 In the immature pigeon both the testes and ovary responded to injections of pregnant mare's serum, the increase in the weight of the ovary being less than that of the testes. 5 The effect of pregnant mare's serum on the immature female fowl has not been reported.

For the experiments here reported pregnant mare's serum containing 50 rat units per cc. (obtained from Dr. H. H. Cole) and oestrin containing 1,000 rat units per cc. prepared by the method of Leonard, Hisaw and Fevold 6 from pregnant mare's urine, were used. The birds were injected daily for the duration of the experimental periods.

In a series of experiments immature white Leghorn males were injected with pregnant mare's serum. The results confirm those of Hamburger 3 for short periods of injection, the size of the testes being increased as much as 6 times, and the comb being much enlarged. In a preliminary experiment 2 birds injected with 4 cc. (200 rat units) of mare's serum daily from 42 to 91 days of age were found to have smaller testes than the control. One of these mated repeatedly with bantam hens but no fertile eggs were obtained. This agrees with histological examination of the testes since, although the tubules and the interstitial tissue were much enlarged, in no case were spermatozoa present. Short periods of injection of pregnant mare's serum have also been found to increase the size of the testes of immature 128-day-old Bronze turkey males (left testis; injected 1411 mg.; control 198 mg.).